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 A163587 A sequence of primes suggested by Ramanujan's: 2*n*log(2*n) < R(n) < 4*n*log(4*n) : floor((2n+m)* log(2*n+m)) if Prime. 1

%I #10 Jul 29 2017 04:20:28

%S 5,23,29,59,307,383,449,691,727,739,751,787,947,971,1009,1021,1097,

%T 1237,1289,1367,1511,1657,1697,1913,2063,2243,2579,2593,2621,2749,

%U 2777,2791,2963,3049,3121,3251,3499,3617,3631,3779,3793,3823

%N A sequence of primes suggested by Ramanujan's: 2*n*log(2*n) < R(n) < 4*n*log(4*n) : floor((2n+m)* log(2*n+m)) if Prime.

%C The result is not A104272, but seems to be distantly related. Duplicates are discarded by the Union[].

%H G. C. Greubel, <a href="/A163587/b163587.txt">Table of n, a(n) for n = 1..1000</a>

%H J. Sondow, <a href="http://arxiv.org/abs/0907.5232"> Ramanujan primes and Bertrand's postulate</a>, Amer. Math. Monthly 116 (2009) 630-635.

%F If floor((2n+m)* log(2*n+m)) is prime, then floor((2n+m)* log(2*n+m)).

%t a[n_] = Floor[2*n*Log[2*n]]; Table[Table[If[PrimeQ[a[n + m]], a[n + m], {}], {m, 0, 2*n}], {n, 1, 100}]; Union[Flatten[%]]

%Y Cf. A104272.

%K nonn,uned

%O 1,1

%A _Roger L. Bagula_, Jul 31 2009

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Last modified September 17 04:31 EDT 2024. Contains 375985 sequences. (Running on oeis4.)